A hybrid vehicle may include a plurality of controllers to operate the vehicle's driveline. For example, the hybrid vehicle may include a vehicle system controller, an engine controller, a transmission controller, an electric machine controller, and a brake controller. The vehicle system controller may request torque responsive to a driver demand torque. The requested torque may be distributed between torque provided via an engine and torque provided via an electric machine. The vehicle system controller may communicate an engine torque request to an engine controller. Further, the vehicle system controller may communicate an electric machine request to an electric machine controller. The engine torque request and the electric machine torque request may be broadcast over a controller area network (CAN), and communication via the CAN may delay the torque requests from reaching the distributed controllers. As a result, the torque delivered via the engine and the electric machine may not accurately track the requested engine and electric machine torque.
Some hybrid vehicle drivelines may include a driveline disconnect clutch for mechanically coupling an engine to an electric machine. The driveline disconnect may transition from an open state to a closed state during engine starting or during periods when the engine is operated at idle speed while the electric machine is propelling the vehicle without assistance from the engine. The engine may be started and accelerated toward speed of an electric machine that is propelling the hybrid vehicle via closing the driveline disconnect clutch. Closing the driveline disconnect clutch may increase a load that is applied to the electric machine, and increasing the load on the electric machine may slow the vehicle and create a driveline torque disturbance if torque of the electric machine is not compensated. However, even if torque of the electric machine is compensated, driveline torque disturbances may occur due to communicating torque requests via the CAN. Therefore, it may be desirable to provide a way of compensating for driveline disconnect clutch torque in vehicle systems where torque requests may be communicated to different controllers.
The inventors herein have recognized the above-mentioned issues and have developed a vehicle system, comprising: an electric machine; an engine; a driveline disconnect clutch mechanically coupled to the engine and the electric machine; and one or more controllers including executable instructions stored in non-transitory memory to adjust an engine torque actuator responsive to driveline disconnect clutch torque, the driveline disconnect clutch torque based on an engine torque and driveline disconnect clutch torque capacity.
By estimating driveline disconnect clutch torque responsive to engine torque and driveline disconnect clutch torque capacity, it may be possible to provide a predicted value of driveline disconnect clutch torque. In particular, the inventors herein have recognized that a prediction of driveline disconnect clutch torque may be provided responsive to driveline disconnect clutch torque capacity, engine torque, and driveline disconnect clutch slip. The prediction is based on a recognition that driveline disconnect clutch torque may transition from a driveline disconnect clutch torque capacity to an engine torque. The blending of driveline disconnect clutch torque capacity and engine torque helps time align electric machine compensation torque with a physical step change in actual driveline clutch torque so that CAN communication delays may be compensated and so that actual engine torque may be adjusted to provide smooth driveline torque progression.
The present description may provide several advantages. Specifically, the approach may provide an improved prediction of driveline disconnect clutch torque so that driveline torque compensation may be improved. Further, the approach may be provided without additional engine sensors or actuators. Further still, the approach may improve engine starting while a vehicle is being propelled via an electric machine.
The above advantages and other advantages, and features of the present description will be readily apparent from the following Detailed Description when taken alone or in connection with the accompanying drawings.
It should be understood that the summary above is provided to introduce in simplified form a selection of concepts that are further described in the detailed description. It is not meant to identify key or essential features of the claimed subject matter, the scope of which is defined uniquely by the claims that follow the detailed description. Furthermore, the claimed subject matter is not limited to implementations that solve any disadvantages noted above or in any part of this disclosure.